This invention relates generally to displacement sensors and more particularly to sensors for use with buried utility pipes.
One of the largest problems encountered in the Midwest and elsewhere during construction involving deep excavations in urban areas has been earth displacement. When it occurs, earth displacement often results in extensive damage to adjacent facilities. This earth displacement is attributed to the fact that some ground includes large amounts of clay or other constituents which have little load bearing capacity and thus have a tendency to flow or subside. Historically, such displacement has been monitored using survey points on retention systems, survey points on the adjacent ground surface, and inclinometers. However, these systems do not provide information regarding the existing utility pipes and other underground structures located in the zone of influence of the excavation.
Some of the devices used in the past to detect displacement of buried utility pipes have been unable to provide sufficient warning of situations in which a utility pipe has acted as a bridge across a sub-surface void. Often such devices would not accurately indicate displacement until the pipe was so stressed as to crack or break.
Further, the devices used in the past often have been quite complicated in structure and thus expensive to manufacture. Additionally, the complicated structure has led to malfunctions during use and thus problems with reliability. Consequently, these complicated devices have required a considerable amount of maintenance in attempts to keep them in proper working order. All these efforts contribute to the cost of construction.
Thus, it is an object of the instant invention to provide a utility pipe displacement sensor which reliably indicates buried utility pipe displacement of even a small magnitude.
It is another object of the instant invention to provide a utility pipe displacement sensor which requires little or no maintenance to keep it in proper working order.
It is yet another object of the instant invention to provide a reliable utility pipe displacement sensor which is not complicated in structure and which is easy and inexpensive to manufacture.
It is a further object of the instant invention to provide a reliable utility pipe displacement sensor which is easy to install and monitor.
These and other objects and advantages of the instant invention will be apparent from the following description and drawings.